ADC with multiple channels settings

dkilshtein9 · ‎2012-12-12

Posted on December 12, 2012 at 10:22

I need to scan 3 ADC channels each second.

I prefer to use ADC3 for all of the channels to save power.

The example below uses ADC3, channel 7 with DMA2 stream 0.

Can I configure the DMA+ADC so I'll will have all three results or do I have to reconfigure it for each ADC channel after each reading?

void ADC_HW_Init(void)

{

ADC_InitTypeDef ADC_InitStructure;

ADC_CommonInitTypeDef ADC_CommonInitStructure;

DMA_InitTypeDef DMA_InitStructure;

GPIO_InitTypeDef GPIO_InitStructure;

/* Enable ADC3, DMA2 and GPIO clocks ****************************************/

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);

/* DMA2 Stream0 channel2 configuration **************************************/

DMA_InitStructure.DMA_Channel = DMA_Channel_2;

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;

DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADC3ConvertedValue;

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;

DMA_InitStructure.DMA_BufferSize = 1;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;

DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;

DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;

DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

DMA_Init(DMA2_Stream0, &DMA_InitStructure);

DMA_Cmd(DMA2_Stream0, ENABLE);

/* Configure ADC3 Channel7 pin as analog input ******************************/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

GPIO_Init(GPIOF, &GPIO_InitStructure);

/* ADC Common Init **********************************************************/

ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;

ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;

ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;

ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;

ADC_CommonInit(&ADC_CommonInitStructure);

/* ADC3 Init ****************************************************************/

ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;

ADC_InitStructure.ADC_ScanConvMode = DISABLE;

ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;

ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfConversion = 1;

ADC_Init(ADC3, &ADC_InitStructure);

/* ADC3 regular channel7 configuration *************************************/

ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_3Cycles);

/* Enable DMA request after last transfer (Single-ADC mode) */

ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);

/* Enable ADC3 DMA */

ADC_DMACmd(ADC3, ENABLE);

/* Enable ADC3 */

ADC_Cmd(ADC3, ENABLE);

}

#adc-dma #adc-stm32

Tesla DeLorean · ‎2012-12-12

Posted on December 12, 2012 at 13:33

You'd need to configure it to do your 3 ADC measurements via DMA, the length of the transfer being 3, and the list inside the ADC being the 3 channels you want.

You probably don't need it to be a circular transfer, as there is so long between each burst of 3 measurements. Use the DMA TC interrupt to call you when all 3 measurements have been completed.

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dkilshtein9 · ‎2012-12-12

Posted on December 12, 2012 at 14:48

Thanks,

I changed the previous code and now I don't get anything at all. The previous code allowed me to read the potentiometer on ADC3 (pf9). Now I get just zeroes.

ADC_InitTypeDef ADC_InitStructure;

ADC_CommonInitTypeDef ADC_CommonInitStructure;

DMA_InitTypeDef DMA_InitStructure;

GPIO_InitTypeDef GPIO_InitStructure;

/* Enable ADC3, DMA2 and GPIO clocks ****************************************/

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF | RCC_AHB1Periph_GPIOA, ENABLE);////////RCC_AHB1Periph_GPIOF only

RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);

/* DMA2 Stream0 channel2 configuration **************************************/

DMA_InitStructure.DMA_Channel = DMA_Channel_2;

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;

DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&val;

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;

DMA_InitStructure.DMA_BufferSize = 3; ////1

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; ////////DMA_MemoryInc_Disable

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;

DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;

DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;

DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

DMA_Init(DMA2_Stream0, &DMA_InitStructure);

DMA_Cmd(DMA2_Stream0, ENABLE);

/* Configure ADC3 Channel7 pin as analog input ******************************/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

GPIO_Init(GPIOF, &GPIO_InitStructure);

//added

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* ADC Common Init **********************************************************/

ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;

ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;

ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;

ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;

ADC_CommonInit(&ADC_CommonInitStructure);

/* ADC3 Init ****************************************************************/

ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;

ADC_InitStructure.ADC_ScanConvMode = DISABLE;

ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;

ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfConversion = 3; ///1

ADC_Init(ADC3, &ADC_InitStructure);

/* ADC3 regular channel7 configuration *************************************/

ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_3Cycles);

ADC_RegularChannelConfig(ADC3, ADC_Channel_4, 1, ADC_SampleTime_3Cycles); ///added

ADC_RegularChannelConfig(ADC3, ADC_Channel_5, 1, ADC_SampleTime_3Cycles); ////added

/* Enable DMA request after last transfer (Single-ADC mode) */

ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);

/* Enable ADC3 DMA */

ADC_DMACmd(ADC3, ENABLE);

/* Enable ADC3 */

ADC_Cmd(ADC3, ENABLE);

ADC_SoftwareStartConv(ADC3);

Nickname12657_O · ‎2012-12-12

Posted on December 12, 2012 at 17:12

Hi,

I think it remains to add the handler for DMA interrupt requests as recommended by Clive1.

Cheers,

STOne-32

Tesla DeLorean · ‎2012-12-12

Posted on December 12, 2012 at 18:32

I don't have a lot of time to invest in this, but a quick scan suggests

unsigned short val[3];

..

DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&val[0];

..

Longer time, and Rank#

/* ADC3 regular channel7 configuration *************************************/

ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_56Cycles);

ADC_RegularChannelConfig(ADC3, ADC_Channel_4, 2, ADC_SampleTime_56Cycles);

ADC_RegularChannelConfig(ADC3, ADC_Channel_5, 3, ADC_SampleTime_56Cycles);

..

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dkilshtein9 · ‎2012-12-13

Posted on December 13, 2012 at 17:34

Thanks for the advice, now I have an interrupt each time conversion is done.

I want to be able to scan the following pins:

Pin 9 on GPIOF (potentiometer)

Pins 1 and 2 on GPIOA

I'm working on the stm3220g-eval board

I use __IO uint16_t val[3] variable to hold the data from the ADC.

I can see the correct data in val[0] but as I turn the potentiometer I see that it affects the data I see in val[1] and val[2]. I think I am missing something with the DMA configuration what results in overwriting my memory.

I have been ''playing'' with this almost the whole day and I just can’t figure this out.

The latest code is below:

__IO uint16_t val[3];

void ADC_HW_Init(void)

{

ADC_InitTypeDef ADC_InitStructure;

ADC_CommonInitTypeDef ADC_CommonInitStructure;

DMA_InitTypeDef DMA_InitStructure;

GPIO_InitTypeDef GPIO_InitStructure;

/* Enable ADC3, DMA2 and GPIO clocks ****************************************/

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF | RCC_AHB1Periph_GPIOA, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);

/* DMA2 Stream0 channel2 configuration **************************************/

DMA_InitStructure.DMA_Channel = DMA_Channel_2;

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;

DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&val[0];

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;

DMA_InitStructure.DMA_BufferSize = 3;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;

DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;

DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;

DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

DMA_Init(DMA2_Stream0, &DMA_InitStructure);

/* Configure ADC3 Channel7 pin as analog input ******************************/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

GPIO_Init(GPIOF, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_2;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* ADC Common Init **********************************************************/

ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;

ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;

ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;

ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;

ADC_CommonInit(&ADC_CommonInitStructure);

/* ADC3 Init ****************************************************************/

ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;

ADC_InitStructure.ADC_ScanConvMode = ENABLE;

ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;

ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfConversion = 3;

ADC_InitStructure.ADC_ExternalTrigConv = 0;

ADC_Init(ADC3, &ADC_InitStructure);

/* ADC3 regular channel7 configuration *************************************/

ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_56Cycles);

ADC_RegularChannelConfig(ADC3, ADC_Channel_1, 2, ADC_SampleTime_56Cycles);

ADC_RegularChannelConfig(ADC3, ADC_Channel_2, 3, ADC_SampleTime_56Cycles);

/* Enable DMA request after last transfer (Single-ADC mode) */

ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);

DMA_ITConfig( DMA2_Stream0, DMA_IT_TC, ENABLE );

DMA_Cmd(DMA2_Stream0, ENABLE);

ADC_DMACmd(ADC3, ENABLE);

ADC_Cmd(ADC3, ENABLE);

ADC_ITConfig(ADC3, ADC_IT_EOC, ENABLE);

NVIC_SetPriority(ADC_IRQn, 0);

NVIC_EnableIRQ(ADC_IRQn);

ADC_SoftwareStartConv(ADC3);

}

void ADC3_IRQHandler(void)

{

ADC_ClearITPendingBit(ADC3, ADC_IT_EOC);

/* Start ADC3 Software Conversion */

ADC_SoftwareStartConv(ADC3);

}

raptorhal2 · ‎2012-12-13

Posted on December 13, 2012 at 18:24

If pin 1 and 2 are not connected to a low impedance signal, crosstalk from pin 9 can cause what you are observing. Connect pin 1 and 2 to ground and try again.

Cheers, Hal

raptorhal2 · ‎2012-12-13

Posted on December 13, 2012 at 18:25

If pin 1 and 2 are not connected to a low impedance signal, crosstalk from pin 9 can cause what you are observing. Connect pin 1 and 2 to ground and try again.

Cheers, Hal